Closure and regulation apparatus for a metallurgical vessel

ABSTRACT

A closure and/or regulation apparatus for controlling the outflow of melt from a metallurgical vessel includes a stator and a rotor rotatable relative to the stator. Additional responsive control of outflow is provided by a chamber that is part of or is connected to an outflow channel that can be connected to a vacuum generator.

BACKGROUND OF THE INVENTION

The invention relates to a closure and/or regulation apparatus forcontrolling the outflow from a metallurgical vessel, in particular forthe close to final dimension casting of steel, and including a statorand a rotor rotatable relative thereto. The stator and rotor areprovided with cooperating sealing surfaces and have through-passages oropenings which terminate in the region of the sealing surfaces in anoutflow channel, and which can be brought into and out of alignment byrotating the rotor.

DE 39 34 601 C1 discloses such a closure and/or regulation apparatus.Through a gas channel provided in the stator or in the rotor, insert gascan be supplied to a gas distribution chamber. This is said to decreasethe wear of the sealing surfaces and through-passages or openings.

DE 38 10 302 C2 discloses a casting apparatus for the continuousmanufacture of metal banding. A controlled gas pressure acts on thesurface of a melt in a casting chamber in order to regular the height ofthe melt level. Such regulation is inert because it must act upon theentire volume of the melt. At the casting nozzle itself no furtherregulation capability is provided.

DE 38 05 071 C2 discloses a closure and/or regulation apparatus in whicha rotor is rotatably supported in a stator transversely to the directionof flow of the melt. This design is especially suitable for continuouscasting of banding or for thin slab casting.

In German Patent Application P 43 19 966, an immersion outlet isemployed as a closure and/or regulation apparatus with a stator and arotor. In an outflow channel is provided a sump chamber which broadensand makes uniform the melt flow for thin slab casting or band casting.

SUMMARY OF THE INVENTION

The invention provides a closure and/or regulation apparatus of theabove type which, in addition to the mechanical capability ofinfluencing the melt flow, also provides a further capability in orderto be able to regulate responsively the melt flow near the outflowthereof.

According to the invention, the above achieved in an underpressurechamber is provided in the stator and/or the rotor. The underpressurechamber can be connected via a channel or conduit disposed in the statorand/or in the rotor with a vacuum generating unit, and is disposed abovethe through-passages or openings and is connected with the outflowchannel.

Thereby, directly in the closure and/or regulation apparatus anunderpressure is made effective. By controlling the underpressure, therate at which the melt flows through the outflow channel is rapidly andresponsively adapted to particular conditions, for example the bathlevel in the metallurgical vessel or the state of wear of thethrough-passages or openings. The underpressure counteracts theferrostatic pressure of the melt in the vessel. By rotating the rotor,the melt flow additionally can be controlled.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention are evident from thefollowing description of exemplary embodiments, with reference to thedrawings, wherein:

FIG. 1 is a cross section of a closure and/or regulation element whereina rotor engages a stator from below;

FIG. 2 is a cross section of a closure and/or regulation element whereina rotor extends from above a stator;

FIG. 3 is a cross section of the rotor according to FIG. 2;

FIG. 4 is a cross section of a further embodiment of a closure and/orregulation element wherein a rotor extends from above a stator;

FIG. 5 is a cross section of a closure and/or regulation element with asump-forming chamber;

FIG. 6 is a cross section of a closure and/or regulation element whereina rotor is supported in a stator rotatably about a transverse axis; and

FIG. 7 is a cross section of a closure and/or regulation element whereina rotor extends from above and into a stator.

DETAILED DESCRIPTION OF THE INVENTION

Corresponding parts are provided with identical reference symbols in thevarious figures.

At the bottom of a metallurgical vessel is disposed a closure and/orregulation element for controlling the outflow of a melt 2.

In the embodiment according to FIG. 1, a rotor 4 is rotatable supportedin a stator 3. The stator 3 and the rotor 4 are in contact with oneanother at respective cylindrical sealing surfaces 5, 6, between whichis formed a sealing gap 7. The stator 3 and the rotor 4 havetherethrough respective through-passages or openings 8, 9. By rotatingthe rotor 4, the openings 8, 9 can be made to more or less coincide,such that outflow of melt 2 from vessel 1 can be controlled by rotationof the rotor 4. The through-passage or opening 9 of the rotor 4 extendsinto a vertical overflow channel 10 which is provided in the rotor 4. Alower end of rotor 4 extends into a chill mold 11.

A front or inner axial end face 12 of stator 3 is opposed by a front oraxial end face 13 of rotor 4. Between the faces 12, 13 is a space which,as will be described later in further detail, forms an underpressurechamber 14. The underpressure chamber 14 is open toward and incommunication with the sealing gap 7. In addition, chamber 14 isconnected with the outflow channel 10 via at least one bore 15. In thestator 3 is a channel conduit 16, which, on the one hand, terminates oropens onto the front face 12 in the underpressure chamber 14 and, on theother hand, extends to outside of the vessel 1 is connected with avacuum generator 17.

The vacuum generator 17 is controllable by a control device 18. Thecontrol device 18 senses, via an upper sensor 19 and a lower sensor 20,the level of the melt in the chill mold 11. Other means for sensing thelevel of the melt in the chill mold 11 can also be provided. To thecontrol device 18 additionally can be connected a drive unit 21 withwhich the rotor 4 is rotatable about a longitudinal axis L.

The operation of the above described closure and/or regulation elementis, for example, as follows.

If by rotating the rotor 4 the through-passages or openings 8, 9 broughtmore or less into alignment, then under the effect of the ferrostaticpressure of the melt 2 in the metallurgical vessel i melt flows throughthe openings 8, 9 and the outflow channel 10 into the chill mold 11. Theferrostatic pressure is a function of the particular height of the meltlevel in the vessel 1. In order to maintain or set the outflow rate ofthe melt 2 constant, the vacuum generator 17 generates an underpressurein the underpressure chamber 14. Such vacuum acts on the one hand in thesealing gap 7 and on the other hand in the outflow channel 10. Suchvacuum counteracts the ferrostatic pressure of the melt 2 in the vessel1, and in addition acts in such a way that melt penetrating into thesealing gap 7 cannot exit toward the outside. By controlling theunderpressure an essentially constant height of the level of the melt inthe chill mold 11 can be attained. It is also possible to achieveuniform filling of the chill mold 11. By control of the underpressure,vortices of the melt flowing through the outflow channel 10 also can beavoided.

In contrast to FIG. 1, in the embodiment according to FIGS. 2 and 3 therotor 4 projects from above into the vessel 1. Rotor 4 fits over oroverlaps on the outside the stator 3 projecting from below into thevessel 1. The outflow channel 10 is formed in the stator 3. Theinterspace between the faces 12 and 13 does not serve as anunderpressure chamber. Rather, underpressure chamber 14 is disposed inthe stator 3 above the through-passages or openings 8, 9 and is an upperextension of the outflow channel 10. The channel or conduit 16 is formedin the stator 3 and has an upper end terminating in the underpressurechamber 14 and extends downwardly therefrom to the outside within thecylindrical sealing face 5 and is connected to vacuum generator 17.

The operation of this embodiment corresponds to that of the embodimentaccording to FIG. 1 with the exception that the underpressure in theunderpressure chamber 14 of FIG. 2 does not act on the sealing gap 7. Ifthe underpressure is also to act on the sealing gap 7, a borecorresponding to bore 15 of FIG. 1 is provided in the face 12 of thestator 3.

In the embodiment according to FIG. 4 the stator 3 is fastened into thevessel 1. Outflow channel 10 extends into an extension piece 26 whichprojects into the chill mold 11. The stator 3 extends above the meltlevel in the vessel 1. The rotor 4 is positioned on the stator 3 and isformed by a tube-shaped member having on the top thereof a head piece 29that is engaged by a drive unit 21 by which the rotor can be rotated.Channel or conduit 16 terminates in underpressure chamber 14 disposed inthe upper region of the stator 3. Channel or conduit 16 extends throughthe rotor 4 and its head piece 29 upwardly to vacuum generator 17. Incomparison to FIG. 2, in FIG. 4 the surface which is acted upon by theunderpressure in the stator 3 is greater.

In the embodiment according to FIG. 5 the stator 3 is disposed below thevessel 1. The rotor 4 is rotatably supported in the stator 3. The rotor4 is not rotatable about the longitudinal axis L but rather is rotatableabout transverse axis Q. The rotor 4 is a cylindrical body through whichthe through-passage or opening 9 extends radially. Outflow channel 10 isin stator 3 below the rotor 4. Below the rotor 4 channel 10 has a sumpchamber 23 which at an overflow edge 24 changes over into a portion 25leading into the chill mold 11. The portion 25 of the outflow channel 10is slit-shaped in cross section for casting a thin slab. Channel orconduit 16 extends in the direction of flow of the melt into portion 25at a location after overflow edge 24 and 25 is connected with vacuumgenerator 17. Channel or conduit 16 also can extend from directly abovethe overflow edge 24 or from above the sump chamber 23. It is alsopossible to provide between the mouth and the channel or conduit 16 anunderpressure chamber expanding channel or conduit 16 toward the mouth.

The operation of this embodiment essentially is identical to thatdescribed above. By controlling the underpressure in the channel orconduit 16, the flow rate of the melt leaving the outflow channel 10 canbe controlled.

In the embodiment according to FIG. 6 rotor 3 and stator 4 are forexample constructed as described in DE 38 05 071 C2. The rotor 4 isrotatable in the stator 3 about a transverse axis Q. The underpressurechamber 14 is located in the stator 3 above through-passages or openings8. The underpressure chamber 14 terminates at the through-passages oropenings 8. The stator 3 and the underpressure chamber 14 extend toabove the level of the melt 2 in vessel 1. The cross-sectional area ofthe underpressure chamber 14 is greater than the cross section of theoutflow channel 10 in the proximity of the rotor 4.

The operation of the embodiment according to FIG. 6 is essentiallyidentical to the described operation. By controlling the underpressurein the underpressure chamber 14, it is possible to control the speed atwhich the melt enters through the through-passages or openings 8 intothe through-passage or opening 9 of the rotor 4.

In the embodiment according to FIG. 7 the rotor 4 projects into thevessel 1 from above. The stator 3 is secured or fastened on the bottomof vessel 1. The rotor 4 and the stator 3 are in contact, in thisembodiment, along semi-spherical sealing surfaces 5', 6'. In the regionof the sealing surfaces 5', 6' are disposed the through-passages oropenings 8, 9. The outflow channel 10 is formed in the stator 3 andcontinues in an extension piece 26 into the chill mold 11. In the regionof the outflow channel 10 the rotor 4 is provided with an outflowopening 27 disposed centrally with respect to the longitudinal axis L.The horizontal cross section of underpressure chamber 14 within theinterior of rotor 4 tapers from the through-passage or opening 9 to theoutflow opening 27. The underpressure chamber 14 extends above the levelof the melt 2 in vessel 1. This augments the effect of the underpressureon the melt flowing from the through-passages or openings 8, 9 to theoutflow opening 27 and, consequently, into the outflow channel 10. Inthe embodiments according to FIGS. 1 to 3, it is also possible to designthe underpressure chamber 14 so that its upper boundary is above thelevel of the melt 2 in the vessel 1. The rotor 4, at the top thereof, issupported oscillatingly such that its spherical sealing surface 6' is inclose contact on the sealing surface 5' of the stator 3 in eachrotational position. The weight and a pressure acting upon a bearingdevice 28 improve the closeness of contact of the sealing surfaces 5',6'. By means of the bearing device 28 the rotor 4 is rotatable about thelongitudinal axis L. Channel or conduit 16 terminating at the top in therotor 4 leads to vacuum generator 17.

We claim:
 1. An apparatus for controlling the discharge of a melt from a metallurgical vessel, said apparatus comprising:a stator and a rotor that is rotatable relative to said stator, said stator and said rotor having cooperating sealing surfaces, and said stator and said rotor having therethrough, in the region of said sealing surfaces, respective through passages that lead to an outflow channel and that can be brought into and out of alignment by rotation of said rotor relative to said stator; an underpressure chamber defined by at least one of said stator and said rotor, said underpressure chamber being located above said through passages and being connected to said outflow channel; and a conduit connected to said underpressure chamber and extending through at least one of said stator and said rotor to connect said underpressure chamber with a source of vacuum.
 2. An apparatus as claimed in claim 1, wherein said underpressure chamber comprises an extension of said outflow channel above said through passages.
 3. An apparatus as claimed in claim 1, wherein said rotor is rotatably mounted within said stator, said outflow channel is defined within said rotor, said underpressure chamber is defined between opposed end faces of said stator and said rotor, and said underpressure chamber is connected to said outflow channel by at least one bore extending through said end fact of said rotor.
 4. An apparatus as claimed in claim 1, wherein said underpressure chamber is connected with a sealing gap defined between said sealing surfaces of said stator and said rotor.
 5. An apparatus as claimed in claim 1, wherein said rotor is rotatably mounted about said stator, said outflow channel is defined within said stator, and said underpressure chamber comprises an extension of said outflow channel closed by an end face of said stator.
 6. An apparatus as claimed in claim 5, wherein said conduit extends through said stator.
 7. An apparatus as claimed in claim 5, wherein said conduit extends upwardly through said rotor.
 8. An apparatus as claimed in claim 1, wherein said underpressure chamber is connected to said through passage of said stator.
 9. An apparatus as claimed in claim 1, wherein said sealing surfaces are cylindrical.
 10. An apparatus as claimed in claim 1, wherein said sealing surfaces are partially spherical.
 11. An apparatus as claimed in claim 10, wherein said underpressure chamber is within said rotor and is connected to said through passages.
 12. An apparatus as claimed in claim 11, wherein said underpressure chamber has a size that reduces below said through passages toward said outflow channel.
 13. An apparatus as claimed in claim 1, wherein said underpressure chamber has a cross section larger than a cross section of said outflow channel.
 14. An apparatus as claimed in claim 1, wherein said stator and said rotor are dimensioned such that, when said apparatus is mounted in a metallurgical vessel, a portion of said underpressure chamber will be above the level of melt in the vessel.
 15. An apparatus for controlling the discharge of a melt from a metallurgical vessel, said apparatus comprising:a stator and a rotor that is rotatable relative to said stator, said stator and said rotor having cooperating sealing surfaces, and said stator and said rotor having therethrough, in the region of said sealing surfaces, respective through passages that lead to an outflow channel and that can be brought into and out of alignment by rotation of said rotor relative to said stator; said outflow channel including a sump chamber leading to a downstream portion, relative to a direction of flow of melt through said outflow channel; and a conduit connected to said outflow channel adjacent one of said sump chamber and said downstream portion to connect said outflow channel to a source of vacuum.
 16. An apparatus as claimed in claim 15, wherein said outflow channel and said conduit extend through said stator.
 17. An apparatus as claimed in claim 15, further comprising an overflow edge between said sump chamber and said downstream portion.
 18. An apparatus as claimed in claim 17, wherein said conduit is connected to said downstream portion immediately downstream of said overflow edge.
 19. An apparatus as claimed in claim 17, wherein said conduit is connected to said outflow channel at a position above said overflow edge. 